Various microprocessor-controlled electric expansion valves using stepping motors have been devised. FIG. 11 is a schematic partial sectional view of one example of a motor type refrigerant three-way valve (cross valve). FIG. 12 are plan views of an open/close state of the valve taken along a line XII—XII in FIG. 11. A three-way valve 100 is provided directly below a stepping motor shown with a reference numeral 200 concentrically with the stepping motor 200, and a rotor 202 is driven by controlling current of a stator 201. The rotor 202 is integrally provided with a rotating shaft 101, and a resin valve body 102 which rotates integrally with the rotating shaft 101 is slidably and concentrically connected an lower end of the rotating shaft 101. A rib 103 projects from a lower surface of the valve body 102, and the rib 103 is contacted to a valve seat 105 under pressure by a compression spring 104.
Communication holes 107a and 107b which are in communication with two pipes 106a and 106b are formed in the valve seat 105 such as to open in a valve chamber 109, the communication holes 107a and 107b are selectively brought into communication with an inflow hole 110 through the valve body 102 in the valve chamber 109. As shown in FIG. 12, the rib 103 has such a shape that surrounds a semicircular recess 111, and one valve body 102 switches a partition of the communication holes 107a and 107b in four modes in accordance with the rotation angle of the rotating shaft 101. That is, if one or both of the communication holes 107a and 107b provided at close two locations are surrounded by the semicircular recess 111, flow between the communication hole and the inflow hole 110 is cut off (closed), and the four modes of open/close states of the communication holes 107a and 107b at two locations shown in FIG. 12 can be selected by rotation angle of the rotating shaft 101.
FIG. 12(a) shows that the communication hole 107a is closed and the communication hole 107b is opened. FIG. 12(b) shows that both the communication holes 107a and 107b are closed. FIG. 12(c) shows that the communication hole 107a is opened and the communication hole 107b is closed. FIG. 12(d) shows that both the communication holes 107a and 107b are opened. In this manner, the valve body 102 is provided concentrically with the motor rotating shaft 101, the valve seat 105 is allowed to rotate under pressure at the same speed as that of the rotating shaft 101, and the four modes of the two communication holes 107a and 107b are switched.
The valve body 102 is rotated concentrically with the rotating shaft 101. The valve body 102 is forcibly rotated against a crimping load caused by a spring 104 which prevents medium from leaking. For this reason, a material of the valve body 102 is limited to those having excellent wear resistance, a thickness of the valve body 102 must be thick for ensuring strength. That is, the valve body 102 can not be designed while assigning the highest priority to adhesion with respect to the valve seat. Therefore, it is not possible to sufficiently select a material which easily adheres. Further, when the valve body 102 is made of resin or the like, a sink mark caused by molding becomes big, and precision with respect to an adhering surface can not be secured.
In view of the above problem, it is an object of the present invention to provide a valve driving device in which a valve seat of a valve body which interrupts or permits the flow of fluid by tightly contacting with an opening peripheral edge and opening or closing an opening can be designed while assigning the highest priority to adhesion to the valve seat, and the valve body can tightly contact the valve seat without increasing a valve-crimping load.